The present invention relates to an overvoltage arrester of the type including a column formed by a multiplicity of arrester elements, arranged in a housing, with shielding elements or members surrounding the column.
An overvoltage arrester of the type described above is disclosed in DE-AS No. 20 37 921. The purpose of the shielding members in the '921 DE-AS is to provide a uniform voltage distribution over the series-connected arrester elements. The desired operation of the overvoltage arrester can be ensured in this manner also if the overvoltage arrester has a grounded metal housing of the type used in pressurized gas-insulated metal-encapsulated switching installations.
Series-connected arrester elements, which may in particular include voltage-dependent resistors and spark gaps, arranged in a column, has long been accepted in overvoltage arrester because it makes the desired series connection possible without the need for additional circuit or connecting elements. However, this arrangment can lead to an extraordinary height of the overvoltage arrester where it is intended to use the overvoltage arrester with very high operating voltages, e.g. 500 kv or more. To reduce the overall height, it is known to distribute the arrester elements over several parallel columns and to use a frame or story like construction. (See, for example, Swiss Pat. Nos. 304,299 and 303,429 and U.S. Pat. No. 2,946,920.) However, those arrangements are not suitable for metal encapsulated arresters because the cost for equalizing the voltage distribution becomes excessively high and the reduction in volume is offset in part by the means required for the voltage distribution. Simple shielding elements or members such those used with the single-column arrangement are not generally applicable to the multiple parallel column, frame-like arrangement.